Manufacture of filaments and films from viscose



Patented Mar. 16, 1926.

.. UNITED STATE-S};

ATENT OFFICE- WILLIAM MENDEL, OF BEVERLY, NEW'JERSEY.

MANUFACTURE or FILAMENTS Ann rrLMs FROM viscose.

No Drawing. ori inal' application filed April 29, 1925, sefiaino. 26,825. ivided a d this application filed April 29, 1925.

To all 107mm it may concern:

Be it known that I, VVILLIABLM NDEL, a citizen of the United States, residing at Beverly, in thecounty of Burlington and State of New Jersey, have invented a certain new and useful Improvement in the l\lanufacture of Filaments and Films from Viscose, whereof the following is a specification.

This is a division of my copending application Serial No. 26,825 filed April 29,1925,

and tlie invention herein claimed includesmethods and means for chemically purifying cellulose products which are primarily formed by conversion of llqlll dvlscose (cellulose 'sulphocarbonate) to coagulated or precipitated cellulose complex, by subjecting such viscose to the action of an acid salt in aqueous solution, either with or without neutral salts or dehydrators, or both.

It is characteristic of all such-products .that the cellulose hydrate is not in a pure state, but mixed with [free sulphur and its derivatives, for instance, sulphides, sulphites, sulphates and thiosulphates. Some of such impurities are soluble, butothers, particularly if an acid bath has been used, are insoluble and increasingly difficult to remove, in accordance with the thickness of the filament or film. Sulphur and its derivatives in such products detract from all of the qualities which make the latter valuable,especially their luster, strength, and elasticity, and the presence of such deleterious matter is manifested by the opacity of the product and the dullness of its ap-' pearance. I

Heretofore, attempts have been a made to remove such impurities'by treatment of such products with sulphites and sulphides, pa-rticularly the latter, and by the use of reducers such as bisulphite or formaldehyde, and oxidizers such as bleaching powder, per manganate of potash or sodium peroxide. However, the action of such materials is incomplete and extremely slow and, consequently, unsatisfactory.

I have discovered that such sulphurous impurities may be eliminated from such cellulose hydrate products by reaction of tri-sodium phosphate (Na POQ therewith; as such reaction converts the sulphur to 'soluble poly-sulphides and thio-sulphates. Therefore, my invention consists in the use of suchfreagent to effect the removal of such Serial No. 26,826.

sulphur'ous impurities from such products.

tion before being subjected to my process herein contemplated. For instance, filaments formed in bi-sulphite should-not be subjected to the action of tri-sodium phosphate until the lapse of, say, four hours. Although the purification and clarification herein contemplated are effected most rapidly .when the cellulose hydrate products are submerged in a hot saturated; solution of tri-sodium phosphate; such a solution quickly becomes clogged with the soluble products of the reaction. Therefore, I find it preferable-to use dilute solutions because, although a longer time is required, the desired result is more economically attained, but it is to be under stood that trisodium phosphate is eflicient for the purpose contemplated at any tem-- perature and in anystate of dilution.

The action of my invention may be effected with great rapidity. For instance, a filament weighing, 1800 denier. which has been formed in an eight per cent sulphuric acid bath, and is then of a dull yellowishwhite chalky appearance; when boiled for two minutes in a saturated aqueous solution of tri-sodium phosphate becomes almost as clear and transparent as glass and, when dried, forms a 300 denier hair, superior in transparency, strength and elasticity to filaments of that size which have been subjected to the action of ordinary reagentsfor which they have been coagulated, into suitable open top containers. I then subject such massed'filaments to the action of three per cent aqueous solution of tri-sodium vphosphate (Na,PO,) at about 50 C., for one and a half to two hours, preferably with intermissions during which the filaments are temporarily separated from the purifying solution and again exposed thereto; for the reason that less time is required to attain the desired result by. such intermittent treatment than by a single treatment during which theviscose products remain covered by the solution of tri-sodium phosphate. Thereafter, such sulphurous impurities, which have thus been rendered soluble, may be readily removed from the cellulose hydrate products by merely rinsing the latter in \VHtQI. The filaments are then dried, preferably under more or less tension. The filaments thus treated are purified ,and clarified and excel in brilliancy of luster, strength and elasticity, but retain a natural greenish-yellow tint which is negligible if the filaments are to be dyed to a darker tint. is desired to dye such filaments with-light colors, such natural greenish-yellow hue is easily removed by bleaching the filaments either before or after they are dried.

Although I have described and claim herein a specific method of carrying out my invention, it is to be understood that the latter includes any and every use of tri-sodium phosphate as a purifier of any kind of product formed from viscose, applied in any manner, in any strength, and at any temperature. For instance, such products may be treated in accordance with my invention during or after. their subjection to a dyeing operation. j I

Therefore, I do not desire tolimit myself to the precise details of construction, ar-

rangement or. procedure herein set forth, as

it is obvious that various modifications may be made therein without departing from the essential features of my invention, as defined in the appended claims.

However,this application includes claims for the species of my invention applicable to cellulose products which have been primarily formed by treatment with salt solutions; specific claims forother processes wherein such products have been primarily formed in baths which) include acid, and

However, if it in an acid salt bath, which consists in sub- .lution of any suitable salt, and eliminating merely by heat,'are respectively included in other applications for Letters Patent of the United States copen'ding herewith.

I claim:

- 1. The process of manufacturing articles from viscose by precipitating such viscose in 5 an aqueous solution containing an acid salt, and subjecting the same to the action of trisodium phosphate (Na ,PO,,).

2. The process of manufacturing articles from viscose by precipitating such viscose in an aqueous solution containing sodium bisulphite, and subjecting the same to the ac-' tion of tri-sodium phosphate (Na PO 3. The process of manufacturing filaments and films from viscose which includes solidifying such viscose in an aqueous solution containing a neutral salt, and treating the resultant product with tri-sodium phosphate in aqueous solution.

4. The method of eliminating sulphur and its derivatives residual in viscose products which have been treated in an aqueous solution containing an acid salt, by subjecting said products to the action of tri-sodium phosphate in aqueous solution.

5. The method of eliminating sulphur and its derivatives residual in viscose products which havebeen treated in an aqueous solution containing an acid salt, by intermittently subjecting s'aid products to the action of tri-sodium phosphate in aqueous solution.

. 6. The process of treating viscose which has been subjected to a solidifying process jecting such products to the action of trisodium phosphate before drying it.

7. The process of treating viscose, whlch conslsts 1n coagulating it in an aqueous soany sulphur derivatives from the cellulose hydrate thus produced, by subjecting the latter to the action of tri-sodium phosphate, in aqueous solution.

In testimony whereof, I have hereunto signed my name at Burlington, New J ersey', this twenty seventh day of April 1925.

WILLIAM MENDEL. 

